Put crabmeat and 1/2 the cheese in a large glass or ceramic bowl and set aside. Sauté onions and celery in butter (I use a deep black iron skillet) until onions are clear, around ten to fifteen minutes. Blend in flour, a little at a time until smooth. Pour in milk and water gradually, stirring constantly. Add egg yolks, salt and peppers. Cook for 5 minutes over medium low heat, stirring often. Pour cooked sauce over crabmeat and cheese and blend well. Transfer mixture to a greased casserole dish and sprinkle the rest of the cheese on top. Bake at 350 F degrees for 15-20 minutes or until light brown. Let cool for 15 minutes.